Franklin 2007 ユーザーズマニュアル

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Application – Single-Phase Motors
BIAC Switch Operation
When power is applied the bi-metal switch contacts are 
closed, so the triac is conducting and energizes the start 
winding. As rpm increases, the voltage in the sensor coil 
generates heat in the bi-metal strip, causing the bi-metal 
strip to bend and open the switch circuit. This removes 
the starting winding and the motor continues to run on 
the main winding alone.
Approximately 5 seconds after power is removed from 
the motor, the bi-metal strip cools suffi ciently to return 
to its closed position and the motor is ready for the next 
start cycle.
Rapid Cycling
The BIAC starting switch will reset within approximately 5 
seconds after the motor is stopped. If an attempt is made 
2-Wire Motor Solid State Controls
to restart the motor before the starting switch has reset, 
the motor may not start; however, there will be current in 
the main winding until the overload protector interrupts 
the circuit. The time for the protector to reset is longer 
than the reset of the starting switch. Therefore, the start 
switch will have closed and the motor will operate. 
A waterlogged tank will cause fast cycling. When a 
waterlogged condition does occur, the user will be 
alerted to the problem during the off time (overload reset 
time) since the pressure will drop drastically. When the  
waterlogged tank condition is detected, the condition 
should be corrected to prevent nuisance tripping of the 
overload protector.
Bound Pump (Sandlocked)
When the motor is not free to turn, as with a sandlocked 
pump, the BIAC switch creates a “reverse impact 
torque” in the motor in either direction. When the sand is 
dislodged, the motor will start and operate in the 
correct direction.
There are two elements in the relay: a reed switch and 
a triac. The reed switch consists of two tiny rectangular 
blade-type contacts, which bend under magnetic fl ux. It 
is hermetically sealed in glass and is located within a coil, 
which conducts line current. When power is supplied to 
the control box, the main winding current passing through 
the coil immediately closes the reed switch contacts. 
This turns on the triac, which supplies voltage to the start 
winding, thus starting the motor.
Once the motor is started, the operation of the QD relay 
is an interaction between the triac, the reed switch and 
the motor windings. The solid state switch senses motor 
speed through the changing phase relationship between 
start winding current and line current. As the motor 
approaches running speed, the phase angle between 
the start current and the line current becomes nearly 
in phase. At this point, the reed switch contacts open, 
turning off the triac. This removes voltage from the start 
winding and the motor continues to run on the main 
winding only. With the reed switch contacts open and 
the triac turned off, the QD relay is ready for the next 
starting cycle.
Single-phase three-wire submersible motors require the 
use of control boxes. Operation of motors without control 
boxes or with incorrect boxes can result in motor failure 
and voids warranty.
Control boxes contain starting capacitors, a starting 
relay, and, in some sizes, overload protectors, running 
capacitors and contactors.
Ratings through 1 hp may use either a Franklin Electric 
solid state QD or a potential (voltage) type starting relay, 
while larger ratings use potential relays.
Potential (Voltage) Relays 
Potential relays have normally closed contacts. When 
power is applied, both start and main motor windings 
are energized, and the motor starts. At this instant, the 
voltage across the start winding is relatively low and not 
3-Wire Control Boxes
enough to open the contacts of the relay.
As the motor accelerates, the increasing voltage across 
the start winding (and the relay coil) opens the relay 
contacts. This opens the starting circuit and the motor 
continues to run on the main winding alone, or the main 
plus run capacitor circuit. After the motor is started the 
relay contacts remain open.
CAUTION: 
The control box and motor are two pieces 
of one assembly. Be certain that the control box and 
motor hp and voltage match. Since a motor is designed 
to operate with a control box from the same
manufacturer, we can promise warranty coverage 
only when a Franklin control box is used with a 
Franklin motor.
CAUTION: Restarting the motor within 5 seconds 
after power is removed may cause the motor overload 
to trip.
QD Relays (Solid State)
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